Why do we hear the sound produced by the humming bees while the sound of vibrations of pendulum is not heard?

cbse
sound
cbse-class-9-science

#1

Why do we hear the sound produced by the humming bees while the sound of vibrations of pendulum is not heard?
Answer:
Humming bees produce sound by vibrating their wings which is in the audible range. In case of pendulum, the frequency is below 20 Hz which does not come in the audible range.